Question:
The chief water conducting elements of xylem in gymnosperms are
The chief water conducting elements of xylem in gymnosperms are
Updated On: Jul 26, 2024
- vessels
- fibres
- transfusion tissue
- tracheids.
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The Correct Option is D
Solution and Explanation
The chief water conducting elements of xylem in gymnosperms are tracheids. These are elongated cells with tapering ends and are dead because of deposition of lignin. These show scalariform, annular, reticulate or bordered pitted thickening. These are the only water conducting xylem elements in both gymnosperm and pteridophytes. Generally vessels are absent in gymnosperm with exceptions like Gnetum, Welxvitschia, Ephedra.
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Concepts Used:
Anatomy of Dicotyledonous and Monocotyledonous Plants
Dicot Root:
- Dicot plants have the taproot system.
- The outermost layer is called the epidermis. The epidermal cells sometimes project out which appear as the root hairs.
- The epidermis is followed by the multi-layered cortex, loosely made of the parenchyma cells with intercellular spaces.
- The inner layer of the cortex is called endodermis, which is tightly packed by the barrel shaped-cells.
- Endodermis is followed by pericycle, which are a few layers of thick-walled parenchyma cells.
- In dicots, the central pith is not distinct.
- There are two to four xylem and phloem.
- The xylem and phloem are remarked by a layer of parenchymatous cells known as conjunctive tissue.
Monocot Root:
Monocot roots do not show much difference in the anatomy from that of the dicot roots.
- Monocot plants possess an adventitious root system.
- As in the dicots, the epidermis forms the outermost layer, followed by cortex, pericycle, endodermis, vascular bundles (xylem and phloem) and pith (random order).
- Pith is conspicuous and large.
- The number of xylem in a monocot is six or more.
- Secondary growth is not seen in the monocot plants.